by Lauren Lim
Photo byRobina Weermeijer onUnsplash
I have never seen my grandmother stand. When I was young, she was always in a wheelchair, only able to murmur short sentences. Eventually, she was bedridden and had a feeding tube in her stomach, as she was unable to chew or swallow. In 2016, she died from complications of Parkinson’s disease. At the time, I only knew Parkinson’s as a sort of incurable illness, and it’s intrigued me ever since.
Parkinson’s disease is the second most common neurological disorder, following Alzheimer’s disease, with about 60,000 Americans diagnosed with the condition each year ("Statistics", 2018). Complications from Parkinson’s are the 14th highest cause of death in the US, according to the Centers for Disease Control and Prevention. As a neurodegenerative disease, Parkinson’s affects the brain’s ability to control movement slowly worsens over time. Patients typically start showing symptoms and are diagnosed around 60 years of age or older; however, early onset Parkinson’s can be diagnosed anywhere between the ages of 21-50 ("Early Onset Parkinson's Disease - APDA", 2021).
Patients start out in the first of five stages of the disease with minor muscle tremors (Greco, 2021). Balance and muscle stiffness worsen throughout the second and third stages, making everyday activities very difficult. In the fourth stage, patients can no longer live independently. Standing, walking, chewing, swallowing, and many other motor functions are impossible by the fifth stage (Greco, 2021). Dementia, the decline of cognitive function over time, is also a common symptom in about 50-80% of Parkinson’s patients (Santhakumar, 2021). These are the major, most well-known symptoms, but different people will experience a range of symptoms and progress through these stages at varying rates, with some living well ten years after diagnosis, while others suffer from severely limited motor ability only two years after diagnosis.
Parkinson’s disease causes the loss over time of dopaminergic neurons, cells that produce dopamine, located in a section of the brain called the substantia nigra, which controls movement ("What Is Parkinson's?", 2021). Dopamine is a neurotransmitter that affects our sleep, heart rate, mood, learning, pleasure, and movement (Cristol, 2021). This deficiency in dopamine is what causes the symptoms of Parkinson’s disease; however, scientists are still looking for the root cause of the disease. Over the years, scientists have identified multiple genetic mutations that have links to Parkinson’s and cause about 10-20% of cases ("Parkinson's Disease Risk Factors and Causes", 2021). It is suspected that a combination of genetic predisposition and environmental factors increase chances of developing Parkinson’s disease. Studies have shown that exposure to pesticides or other harmful chemicals and head trauma can increase the likelihood of the condition; however, scientists acknowledge that these are only contributing factors rather than true causes ("Parkinson's Disease Risk Factors and Causes", 2021). Other research has studied oxidative stress on mitochondria, a vital organelle in cells that produces usable chemical energy, among other potential causes (Jabr, 2010). Much research has been centered around determining the cause of dopaminergic cell death.
Despite considerable research to identify a cause and effective treatment for Parkinson’s, there is currently no cure. There are several medicines that can treat the motor dysfunction symptoms of the disease, but these come with other side effects, such as impaired cognitive function. Treatments to slow or stop the progression of the disease itself are still in development. One recent trial in Massachusetts into a natural antioxidant, urate, yielded disappointing results (Murez, 2021). Research on urate suggested that it could reduce oxidative damage to cells, so patients with early stage Parkinson’s were treated with inosine—a chemical that increases urate levels. However, after two years of monitoring the study participants, the disease progression was not noticeably slowed. While these results were not ideal, Dr. Michael Schwarzschild, a professor of neurology at Harvard Medical School and a neurologist at Mass General, claimed that the study doesn’t completely rule out the effect of urate, only implying that increasing its levels would not slow disease progression.
As our life expectancy increases with modern levels of healthcare, neurodegenerative diseases will only become more and more common, and Parkinson’s is a prominent example of that. As I think of my grandmother’s last years, I know that living longer is not enough; just as importantly, we must look to science to maintain our quality of life. While progress is slow, scientists are hopeful that they can identify the root cause of Parkinson’s and develop a successful cure in the near future.
References
Cristol, H. (2021). What Is Dopamine?. WebMD. Retrieved 1 October 2021, from https://www.webmd.com/mental-health/what-is-dopamine.
Early Onset Parkinson's Disease - APDA. American Parkinson Disease Association. (2021). Retrieved 2 October 2021, from https://www.apdaparkinson.org/what-is-parkinsons/early-onset-parkinsons-disease/.
Greco, P. (2021). What are the 5 Stages of Parkinson's Disease? Here's What Happens at Every Stage. Health.com. Retrieved 1 October 2021, from https://www.health.com/condition/parkinsons-disease/parkinsons-disease-stages.
Jabr, F. (2010). Parkinsonian Power Failure: Neuron Degeneration May Be Caused by a Cellular Energy System Breakdown. Scientific American. Retrieved 1 October 2021, from https://www.scientificamerican.com/article/parkinsons-mitochondria/.
Murez, C. (2021). Trial Into Antioxidant for Parkinson's Disease Yields Disappointing Results. WebMD. Retrieved 1 October 2021, from https://www.webmd.com/parkinsons-disease/news/20210917/trial-into-antioxidant-for-parkinsons-disease-yields-disappointing-results.
Parkinson's Disease Risk Factors and Causes. Johns Hopkins Medicine. (2021). Retrieved 1 October 2021, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/parkinsons-disease/parkinsons-disease-risk-factors-and-causes.
Santhakumar, S. (2021). Lewy body dementia and Parkinson's disease. Medicalnewstoday.com. Retrieved 1 October 2021, from https://www.medicalnewstoday.com/articles/lewy-body-parkinsons#lewy-body-dementia.
Statistics. Parkinson's Foundation. (2018). Retrieved 1 October 2021, from https://www.parkinson.org/Understanding-Parkinsons/Statistics.
What Is Parkinson's?. Parkinson's Foundation. (2021). Retrieved 1 October 2021, from https://www.parkinson.org/understanding-parkinsons/what-is-parkinsons.
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